1. Field of the Invention
This invention relates generally to fluid filters employed in connection with internal combustion engines. More particularly, the present invention relates to fuel filters and lubricating oil filters having a replaceable cartridge for removing foreign particles and/or separating water from the fuel supply or oil system of an internal combustion engine.
2. Description of the Related Art
Conventionally, fuel filters employ a disposable filter cartridge which is replaced at pre-established intervals of filter usage. The filter cartridge is removably installed to a filter base or header. While a number of different methods and structures may be used to join the filter cartridge to the base, all of the methods and structures require general alignment of a filter cartridge axis with a base axis. Filter assemblies to which the invention relates may be mounted in locations where access is limited. It has therefore been the practice to provide these frequently serviced assemblies with securement means that do not require the use of tools. For some filter assemblies to which the invention relates a retaining collar or ring is employed to facilitate the securement function. A resilient bias between the base, filter cartridge and/or retaining collar is required to secure the cartridge to the base such that the cartridge/base relationship resists vibration and shock prevalent in the automotive environment. The axial resilient bias is associated with a reduced torque on the securement means to allow removal of the installed filter cartridge from the base by hand.
Typically, a metallic spring is disposed between the base and filter cartridge or engaged against the retaining collar to provide the required resilient biasing. The spring can be relatively complex. For example, U.S. Pat. No. 5,203,994 discloses a three-dimensional star shaped spring disposed between the base and filter cartridge. U.S. Pat. No. 5,302,284 discloses a wave spring disposed between the filter cartridge and retaining collar. The use of a separate metallic spring represents cost and complexity to the filter assembly, both for the manufacture of the spring as well as for its installation onto the base. Further, these springs break down over time and may be lost or omitted by service personnel, reducing their effectiveness.
Briefly stated, the invention in a preferred form is a filter cartridge incorporating a novel multi-function grommet spring which both provides an axial biasing force for securement purposes and a sealing function for fluidly sealing the filter cartridge with a base.
The base is of a type having an inlet and an outlet fluidly connected to the engine fuel system. A replaceable filter cartridge is mountable to the base. The replaceable cartridge includes a generally cylindrical housing that houses the fuel filter elements. The top surface of the cartridge defines a circular opening for receiving a fluid flow from the base and for discharging a filtered fluid flow to the base. A grommet spring is mounted to the top surface coaxially around the opening. One end of the grommet spring preferably projects substantially orthogonally from the top surface of the cartridge to form a resilient annular contact surface. The opposing end of the grommet spring is enclosed within the filter cartridge and defines a circular seal portion with a radially inwardly facing seal lip.
When the filter cartridge is secured to the filter base, the seal lip circumferentially contacts a fluid conduit projecting from the base to establish the fluid circuit between the filter cartridge and filter base. In addition, the projecting contact surface is compressed between the filter base and top surface of the cartridge, resiliently biasing the filter cartridge away from the filter base.
An object of the invention is to provide a new and improved disposable filter cartridge.
Another object of the invention is to provide a fuel cartridge biasing structure that is efficient, cost effective and reliable.
A further object of the invention is to provide a new and improved filter cartridge comprising an improved biasing structure for releasably biasing the cartridge to secure installed position in a fuel filter assembly.
Other objects and advantages of the invention will become apparent from the specification and the drawings.